Internal parasites of the dog
The most common internal parasite of the dog is the roundworm (ascarid), which when vomited or passed through the rectum will often coil into a ring. These parasites are similar to strands of spaghetti and can be passed from the mother to the puppies. When you take your dog in for a checkup, take along a fresh stool sample. If it is positive for roundworms, your vet will prescribe a safe worming agent, which will have to be repeated in two weeks to break the life cycle of the roundworms. Roundworms can not only affect the gastrointestinal tract but can pass into the lungs and cause damage there. You might suspect roundworms if your dog has an enlarged belly, poor weight gain, diarrhea or vomiting.
Hookworms are blood-suckers and can be transmitted either orally or by larval penetration of the skin. They attach themselves to the walls of the small intestine and feed on the blood of the dog. If left untreated, they can cause severe anemia and weight loss. Hookworms are much smaller than roundworms and are rarely detected by the owner. When treating your dog for hookworms, be sure to remove stools from your premises as the larvae can live in the soil; it may be necessary to treat your yard.
As adults, whipworms live in the caecum (a portion of the large intestine comparable to our appendix) and, like hookworms, are ingested from contaminated soil. If untreated, whipworms can cause diarrhea sometimes mixed with blood, anemia, weight loss and a prolapsed colon, a serious condition in which the rectal tissue of the lower colon everts and protrudes from the anus.
Tapeworm eggs are found in small, ricelike segments released from the anus of an infected dog. These segments are mobile and fall to the ground, where the eggs can be ingested by flea larvae in the environment. The tapeworm continues its development in the flea. When the flea is swallowed by the dog during his normal grooming, the tapeworm is released and completes its development in the dog.
Heartworm disease is caused by a filarial worm that is carried by mosquitoes. An early symptom is a cough, followed by the more serious symptoms of heart failure, because in the final stages the worm lives within the heart. Treatment for heartworm can be very hard on a dog and it is far better to give your dog a daily or monthly heartworm preventative. Some of the newer once-a-month heartworm preventatives also eliminate hookworms, roundworms and whipworms. Ask your vet what he or she recommends.
To avoid contamination or reinfestation of internal parasites, keep your premises clean and free of fecal matter by disposing of it in a proper manner. Make sure your dog has clean bedding and regular fecal checks approximately every six months. If you see him biting at his rear or trying to rub it on the floor, this could be an indication of worms.